Remove UTF-8 encoded BOM

It cause compilation failure with javac
Relate: http://stackoverflow.com/q/9811382
Use holder and convertView in BookModelAdapter and PageModelAdapter
Only refresh data from database when needed

On Novel with many volumes and chapters, refresh data could take several seconds.
=> only refresh data when go back from DisplayLightNovelContentActivity, and make it happens
in new thread.
Merge pull request #164 from xuanduc987/working

Some fixes